Add a simple rawmemchr implementation. Use strlen for rawmemchr(s, '\0') as it

is the fastest way to search for '\0'.  Otherwise use memchr with an infinite
size.  This is 3x faster on benchtests for large sizes.  Passes GLIBC tests.

	* sysdeps/aarch64/rawmemchr.S (__rawmemchr): New file.
	* sysdeps/aarch64/strlen.S (__strlen): Change to __strlen to avoid PLT.

1 files changed, 42 insertions, 0 deletions

diff --git a/sysdeps/aarch64/rawmemchr.S b/sysdeps/aarch64/rawmemchr.S
new file mode 100644
index 0000000000..ec958e8f54
--- /dev/null
+++ b/sysdeps/aarch64/rawmemchr.S
@@ -0,0 +1,42 @@
+/* rawmemchr - find a character in a memory zone
+
+   Copyright (C) 2015 Free Software Foundation, Inc.
+
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+/* Special case rawmemchr (s, 0) as strlen, otherwise tailcall memchr.
+   Call strlen without setting up a full frame - it preserves x14/x15.
+*/
+
+ENTRY (__rawmemchr)
+	cbz	w1, L(do_strlen)
+	mov	x2, -1
+	b	__memchr
+
+L(do_strlen):
+	mov	x15, x30
+	cfi_return_column (x15)
+	mov	x14, x0
+	bl	__strlen
+	add	x0, x14, x0
+	ret	x15
+
+END (__rawmemchr)
+weak_alias (__rawmemchr, rawmemchr)
+libc_hidden_builtin_def (__rawmemchr)